Cell Signalling and Transduction
In the signal transduction mechanism known as protein phosphorylation

the signaling molecule binds to a surface receptor
phosphorylated proteins act with enzymes to trigger the signal cascade
All of these
receptor kinases play a key role in triggering the signal cascade

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Cell Signalling and Transduction
The binding of ligands to many G-proteins linked receptors leads to shortlived

decrease in the concentration of certain intracellular signaling molecules called second messenger
increase in the concentration of certain extracellular signaling molecules called first messenger
increase in the concentration of certain intracellular signaling molecules called second messenger
decrease in the concentration of certain extracellular signaling molecules called first messenger

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Cell Signalling and Transduction
In terms of cell communication, what do bacterial pathogens such as cholera and anthrax have in common?

They alter the chemical structure of key signaling molecules
They destroy the receptors for key signaling molecules
They block the normal functioning of signal transduction mechanisms
They prevent the production of key signaling molecules

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Cell Signalling and Transduction
A cell is known to respond to a particular signaling molecule. Which of the following must be true of this cell?

It is in the heart muscle
It is also the site of production for the signaling molecule
It is incapable of signal transduction
It contains the receptor for the signaling molecule

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